Astronomy Picture of the Day

Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.

2008 July 30

The International Space Station Transits the Sun Credit & Copyright: Martin Wagner

Explanation: That's no sunspot.
It's the
International Space Station (ISS)
caught by chance passing in front of the Sun.
Sunspots, individually, have a dark central
umbra, a lighter surrounding penumbra,
and no solar panels.
By contrast, the ISS is a complex and multi-spired mechanism,
one of the largest and most sophisticated machines ever created by
humanity.
Also, sunspots occur on the
Sun, whereas the ISS orbits the
Earth.
Transiting the Sun is not very unusual for the
ISS, which orbits the Earth about every 90 minutes,
but getting one's timing and equipment just right for a
great image is rare.
Strangely, besides that fake spot, the Sun, last week,
lacked any real sunspots.
Sunspots have been
rare
on the Sun since the dawn of the current
Solar Minimum,
a period of low solar activity.
Although fewer sunspots have been
recorded during this
Solar Minimum
than for
many previous decades, the low solar activity is
not, as yet, very unusual.